Various blade shapes or methods of installing a main plate and a side plate have been proposed for improving performance, such as reducing power consumption, operation noise, or the like, of a turbo fan used in a conventional ceiling-embedded type air conditioner or the like.
For example, in patent literature 1 (Japanese Patent Registration No. 273095), a blade having a distorted structure, in which a side plate of an outer circumference of the blade is obliquely formed to be located in a half-turn direction from a main plate and conversely an inner circumference of the blade is obliquely formed to be opposite the outer circumference, is proposed. Further, patent literature 2 (Japanese Patent Registration No. 1998-196591) discloses an end portion of a side plate of an inner circumferential side of a blade, which is formed to be inclined in a rotational direction thereof.
However, when only improvement of performance is pursued, a shape of a turbo fan is complicated and difficulty in manufacturing increases such that costs can be increased. For example, when the turbo fan described above is formed of a resin by injection molding, a complicated and costly mold becomes necessary or side plates or blades are separately molded and then each of the side plates or blades needs to be assembled by fusing.